At the University of Hokkaido, School of Dentistry a combination of extraoral and intraoral suction is used since the occurrence of the Covid-19 pandemic. The standard high volume intraoral suction is complemented by an extra high volume, very powerful suction device that can aspirate high volumes of air per time. This creates an airflow that aspirates all aerosols away from the mouth of the patient and away from the caretaker (Dentist or Dental Hygienist). Prof. Sano claims that due to this set up there were no covid-19 transmissions during dental treatmaent at the University of Hokkaido.
Multiple factors are eliminating/reducing aerosol contamination during patient treatment. First a combination of the powerful sucction devices. The extremely powerful extraoral suction (lower circle) is removong all the aerosols left by the powerful intraoral suction (upper circle). The caretaker is wearing a medical grade face mask, eye protection and a face shield. Note that there are no droplets on the face shield. Furthermore, the dentist works with indirect view via dental mirror, allowing her to have her head far away from the source of aerosols. A resident is working to assiste the dentist.